Is there a way to get variance in albedo channel as well as in the bump and roughness?

Have a look; no clue if it works correctly for bump, fresnel scale and roughness.
No code error messages at least.
Just play around; consists of 3 textures.

If you want to test it with only one texture; just change the value in all shader channels from "NUM_TEXTURES = 3" to "NUM_TEXTURES = 1"... and so on and so forth.
Code for provided channels should work in similar channels for different shaders; depends on what vec or real is being used by it.

Maybe someday we could add shared parameters for the grid noise options... to get more control.